Series MIM structures compatible with RRAM process

ABSTRACT

The present disclosure relates to a method of forming an integrated circuit that prevents damage to MIM decoupling capacitors, and an associated structure. In some embodiments, the method comprises forming one or more lower metal interconnect structures within a lower ILD layer over a substrate. A plurality of MIM structures are formed over the lower metal interconnect structures, and one or more upper metal interconnect structures are formed within an upper ILD layer over the plurality of MIM structures. Together the lower and upper metal interconnect structures electrically couple the plurality of MIM structures in a series connection between a first voltage potential and a second voltage potential. By placing the MIM structures in a series connection, dissipation of the first voltage potential (e.g., a supply voltage) is spread out over the MIM structures, thereby reducing the voltage potential difference between electrodes of any one of the MIM structures.

BACKGROUND

Integrated chips are formed on semiconductor die comprising millions or billions of transistor devices. The transistor devices are configured to act as switches and/or to produce power gains so as to enable logical functionality for an integrated chip (e.g., form a processor configured to perform logic functions). Integrated chips often also comprise passive devices, such as capacitors, resistors, inductors, varactors, etc. Passive devices are widely used to control integrated chip characteristics (e.g., gain, time constants, etc.) and to provide a single integrated chip with a wide range of different functionalities (e.g., manufacturing analog and digital circuitry on the same die).

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 illustrates some embodiments of an integrated chip comprising a voltage divider having a plurality of MIM (metal-insulator-metal) structures.

FIG. 2 illustrates some embodiments of a schematic diagram of a voltage divider comprising a plurality of MIM structures.

FIGS. 3-6 illustrate some alternative embodiments of integrated chip comprising a voltage divider having a plurality of MIM capacitors.

FIG. 7 illustrates some additional embodiments of an integrated chip comprising a voltage divider having a plurality of MIM decoupling capacitors.

FIGS. 8-13 illustrate some embodiments of cross-sectional views showing a method of forming an integrated chip comprising a voltage divider having a plurality of MIM capacitors.

FIG. 14 illustrates some embodiments of a method of forming an integrated chip comprising a voltage divider having a plurality of MIM capacitors.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

MIM (metal-insulator-metal) capacitors are a particular type of capacitor, having a top metal plate and a bottom metal plate separated by a capacitor dielectric, which are often implemented in integrated circuits. MIM capacitors are often integrated into a back-end-of-the-line (BEOL) metallization stack, at a position that is vertically disposed between an underlying first metal layer and an overlying second metal layer. MIM capacitors can be used as decoupling capacitors configured to mitigate switching noise on a power supply line caused by switching of logic devices within an integrated chip. For example, MIM capacitors may be used to reduce switching noise due to a voltage drop on a power supply line caused by simultaneous switching of input/output (I/O) and core circuits within an integrated chip. Without decoupling capacitors this switching noise may increase signal delay, thereby reducing the operating frequency of an integrated circuit, and inadvertently causing state transitions in logic circuits within the integrated circuit.

As the size of integrated chip components decreases, the dielectric layer reliability voltage limit (e.g., time dependent dielectric breakdown voltage, etc.) of modern MIM capacitor also decreases, limiting the application of a MIM capacitor as a decoupling capacitor. For example, for a MIM capacitor having a dielectric layer reliability voltage limit of 0.8 volts, a voltage difference between electrodes of the MIM capacitor over 0.8 volts may damage the dielectric layer of the MIM capacitor. However, in modern integrated chip, the supply voltage is often greater than the dielectric layer reliability voltage limit (e.g., time dependent dielectric breakdown voltage) of a MIM decoupling capacitor, resulting in damage to the MIM decoupling capacitor.

Some embodiments of the present disclosure relates to a method of forming an integrated circuit that prevents damage to MIM decoupling capacitors, and an associated structure. In some embodiments, the method comprises forming one or more lower metal interconnect structures within a lower inter-level dielectric (ILD) layer over a substrate. A plurality of MIM structures are formed over the one or more lower metal interconnect structures. One or more upper metal interconnect structures are formed within an upper ILD layer over the plurality of MIM structures. Together the lower and upper metal interconnect structures electrically couple the plurality of MIM structures in a series connection between a first voltage potential and a second voltage potential. By placing the plurality of MIM structures in a series connection, dissipation of the first voltage potential (e.g., a supply voltage) is spread out over the plurality of MIM structures, thereby reducing the voltage potential difference between electrodes of any one of the MIM structures. Reducing the voltage potential difference, allows for the voltage potential across a MIM structure to be held below the reliability voltage limit (e.g., time dependent dielectric breakdown voltage, etc.), thereby allowing the MIM structures to be used as a decoupling capacitor in a system having a supply voltage greater than the reliability voltage limit

FIG. 1 illustrates some embodiments of an integrated chip 100 comprising a voltage divider circuit 101 having a plurality of MIM (metal-insulator-metal) structures.

The integrated chip 100 comprises a substrate 102. In some embodiments, the substrate 102 may comprise a semiconductor material, such as silicon, having an n-type or a p-type doping. A back-end-of-the-line (BEOL) metallization stack is arranged over the substrate 102. The BEOL metallization stack comprises a plurality of MIM structures, 108 a and 108 b, arranged within an inter-level dielectric (ILD) layer 104 disposed over the substrate 102. The plurality of MIM structures, 108 a and 108 b, respectively comprise a first electrode and a second electrode separated by a dielectric layer. For example, the MIM structures in some embodiments comprise a lower electrode 110 that is vertically separated from an upper electrode 114 by a capacitor dielectric layer 112. The ILD layer 104 may comprise one or more separate dielectric layers (e.g., a low-k dielectric material, an ultra low-k dielectric material, etc.) stacked onto one another over the substrate 102. For example, the ILD layer may comprise a lower ILD layer 104 a and an upper ILD layer 104 b. The ILD layer 104 laterally separates the plurality of MIM structures, 108 a and 108 b, from one another.

The BEOL metallization stack further comprises a plurality of metal interconnect layers arranged within the ILD layer 104. The plurality of metal interconnect layers comprise a lower metal interconnect layer 106 and an upper metal interconnect layer 116. The ILD layer 104 vertically separates the lower metal interconnect layer 106 from the substrate 102. The lower electrodes 110 of the plurality of MIM structures, 108 a and 108 b, are in contact with the lower metal interconnect layer 106, and the upper electrodes 114 are in contact with the upper metal interconnect layer 116. In some embodiments, the lower metal interconnect layer 106 and the upper metal interconnect layer 116 may comprise one or more metal interconnect structures laterally separated from one another by the ILD layer 104. For example, the lower metal interconnect layer 106 may comprise a first lower metal interconnect structure 106 a and a second lower metal interconnect structure 106 b, and the upper metal interconnect layer 116 may comprise a first upper metal interconnect structure 116 a and a second upper metal interconnect metal structure 116 b. In some embodiments, the lower metal interconnect layer 106 and the upper metal interconnect layer 116 may comprise metal wire layers configured to provide for an interconnection in a lateral direction (i.e., parallel to an upper surface of the substrate 102).

The lower metal interconnect layer 106 and the upper metal interconnect layer 116 are comprised within a conductive path that electrically connects the plurality of MIM capacitors, 108 a and 108 b, in a series connection (i.e., along a single electrically conductive path) extending between a first voltage potential V₁ and a second voltage potential V₂, which is less than the first voltage potential V₁. For example, as shown in integrated chip 100, an electrode of a first MIM structure 108 a is coupled to an electrode of a second MIM structure 108 b by way of a conductive path comprising the lower metal interconnect layer 106, the upper metal interconnect layer 116, and a via 118 vertically extending between the lower metal interconnect layer 106 and the upper metal interconnect layer 116. In some embodiments, the first voltage potential V₁ may be a supply voltage (V_(DD)) and the second voltage potential V₂ may be a ground voltage (i.e., a voltage potential of zero).

Connecting the plurality of MIM structures, 108 a and 108 b, in series between the first voltage potential V₁ and the second voltage potential V₂, causes a voltage drop between the first voltage potential V₁ and the second voltage potential V₂ to be distributed (i.e., spread out) between the plurality of MIM structures, 108 a and 108 b. This results in one or more intermediate voltage nodes V_(int1) with voltage potentials between the first voltage potential V₁ and the second voltage potential V₂ (e.g., each of the plurality of MIM structures, 108 a and 108 b, will respectively provide for a voltage drop less than the difference between the first voltage potential V₁ and the second voltage potential V₂). By generating one or more intermediate voltages along the conductive path coupling the plurality of MIM structures, 108 a and 108 b, the potential voltage difference between electrodes of any one of the plurality of MIM structures, 108 a and 108 b, can be held to a relatively low value that is less than a reliability voltage limit (e.g., time dependent dielectric breakdown voltage, etc.), thereby preventing damage to the capacitor dielectric layer 112 of the MIM structures, 108 a and 108 b.

FIG. 2 illustrates some embodiments of a schematic diagram of a disclosed voltage divider 200 comprising a plurality of MIM structures.

The voltage divider 200 comprises a plurality of MIM structures, C_(MIM) _(_) ₁ and C_(MIM) _(_) ₂ connected in series between a first voltage potential V₁ and a second voltage potential V₂. The plurality of MIM structures, C_(MIM) _(_) ₁ and C_(MIM) _(_) ₂, may respectively comprise a capacitance C_(n) (n=1, 2) and an intrinsic resistance R_(n) (n=1, 2). The plurality of MIM structures, C_(MIM) _(_) ₁ and C_(MIM) _(_) ₂, respectively cause a voltage drop to occur between the first voltage potential V₁ and the second voltage potential V₂, which is proportional to a capacitance and/or intrinsic resistance of a MIM structure. For example, a first MIM structure C_(MIM) _(_) ₁ will cause a first voltage drop ΔV₁ proportional to the capacitance and/or intrinsic resistance of the first MIM structure C_(MIM) _(_) ₁, and a second MIM structure C_(MIM) _(_) ₂ will cause a second voltage drop ΔV₂ proportional to the capacitance and/or intrinsic resistance of the second MIM structure C_(MIM) _(_) ₂. The voltage drop ΔV₁ of the first MIM capacitor C_(MIM) _(_) ₁ results in an intermediate voltage, having a value between the first voltage potential V₁ and the second voltage potential V₂, at an intermediate voltage node V_(int) located between the first MIM structure C_(MIM) _(_) ₁ and the second MIM structure C_(MIM) _(_) ₂.

In some embodiments, the first and second MIM structures, C_(MIM) _(_) ₁ and C_(MIM) _(_) ₂, may have substantially same capacitance and/or resistance values. In such embodiments, the voltage dissipated by the first and second MIM structures, C_(MIM) _(_) ₁ and C_(MIM) _(_) ₂, is equal. For example, for a first voltage potential with a value of V₁ approximately equal to 1.2 V, the first voltage drop ΔV₁ will be approximately 0.6 V and the second voltage drop V₂ will be approximately 0.6 V, resulting in a voltage potential at the intermediate voltage node V_(int) of approximately 0.6 V.

Since the difference in voltage potential between the first voltage potential V₁ and the second voltage potential V₂ is shared between the plurality of MIM structures, C_(MIM) _(_) ₁ and C_(MIM) _(_) ₂, each voltage drop ΔV₁ and ΔV₂ can be made to be smaller than a reliability voltage limit (e.g., time dependent dielectric breakdown voltage, etc.) of the MIM structures, C_(MIM) _(_) ₁ and C_(MIM) _(_) ₂, so that the MIM structures can be used as decoupling capacitors.

FIG. 3 illustrates some alternative embodiments of an integrated chip 300 comprising a voltage divider having a plurality of MIM capacitors.

Integrated chip 300 comprises a dielectric structure 301 comprising a plurality of dielectric layers 302 a-302 c stacked onto one another. In various embodiments, the plurality of dielectric layers 302 a-302 c may comprise a low-k dielectric material, an ultra low-k dielectric material, an extreme low-k dielectric material, and/or an oxide. A first MIM capacitor 306 a and a second MIM capacitor 306 b are arranged within the dielectric structure 301. The first MIM capacitor 306 a and the second MIM capacitor 306 b respectively comprise a lower electrode 308 and an upper electrode 312 separated by a capacitor dielectric layer 310.

In various embodiments, the lower electrode 308 and the upper electrode 312 may comprise platinum (Pt), aluminum-copper (AlCu), titanium nitride (TiN), gold (Au), titanium (Ti), tantalum (Ta), tantalum nitride (TaN), tungsten (W), tungsten nitride (WN), and/or copper (Cu), for example. In various embodiments, the capacitor dielectric layer 310 may comprise nickel oxide (NiO), titanium oxide (TiO), hafnium oxide (HfO), zirconium oxide (ZrO), zinc oxide (ZnO), tungsten oxide (WO₃), aluminum oxide (Al₂O₃), tantalum oxide (TaO), molybdenum oxide (MoO), and/or copper oxide (CuO), for example.

The first and second MIM capacitors, 306 a and 306 b, are connected in series between a supply voltage V_(DD) and a ground voltage V_(GND) (i.e., zero volts) by way of a single metal layer continuously extending between the first MIM capacitor 306 a and the second MIM capacitor 306 b. For example, in some embodiments, the first MIM capacitor 306 a has an upper electrode 312 connected to a first upper metal interconnect structure 314 a contacting a power rail (i.e., a power supply line) held at the supply voltage potential V_(DD) and a lower electrode 308 connected to a lower metal interconnect structure 304. The lower metal interconnect structure 304 continuously extends to a lower electrode 308 of the second MIM capacitor 306 b, which has an upper electrode 312 connected to a second upper metal interconnect structure 314 b held at the ground voltage potential V_(GND).

Although integrated chip 300 illustrates the lower electrodes 308 of the first and second MIM capacitors, 306 a and 306 b, as being connected by a lower metal interconnect continuously extending between the electrodes, it will be appreciated that in other embodiments, the upper electrodes 312 of the first and second MIM capacitors, 306 a and 306 b, may be connected by an upper metal interconnect structure continuously extending between the electrodes.

In some embodiments, the first and second MIM capacitors, 306 a and 306 b, may be cup-shaped capacitors. The cup-shaped capacitors comprise a lower electrode 308 having a ‘U’ shape with a cavity. A capacitor dielectric layer 310 is arranged within the lower electrode 308 and extends from within the cavity in the lower electrode 308 to a location overlying the lower electrode 308. An upper electrode 312 is arranged on the capacitor dielectric layer 310 and extends from within the cavity in the lower electrode 308 to a location overlying the capacitor dielectric layer 310. In alternative embodiments, the first and second MIM capacitors, 306 a and 306 b, may have alternate structures (e.g., a planar capacitor structure, a bar-shaped capacitor structure, etc.)

FIG. 4 illustrates some alternative embodiments of an integrated chip 400 comprising a voltage divider having a plurality of MIM capacitors.

Integrated chip 400 comprises a first MIM capacitor 404 a, a second MIM capacitor 404 b, and a third MIM capacitor 404 c arranged in series between a supply voltage V_(DD) and a ground voltage V_(GND). The first MIM capacitor 404 a has an upper electrode 410 connected to a first upper metal interconnect structure 412 a held at the supply voltage V_(DD) and a lower electrode 406 connected to a first lower metal interconnect structure 402 a. The first lower metal interconnect structure 402 a continuously extends between the lower electrode 406 of the first MIM capacitor 404 a and a lower electrode 406 of the second MIM capacitor 404 b. The second MIM capacitor 404 b has an upper electrode 410 connected to a second upper metal interconnect structure 412 b that continuously extends to an upper electrode 410 of the third MIM capacitor 404 c. The third MIM capacitor 404 c has a lower electrode 406 connected to a second lower metal interconnect structure 402 b held at the ground voltage V_(GND).

Each of the plurality of MIM capacitors 404 a-404 c cause a voltage drop to occur that is proportional to a capacitance and/or resistance of the MIM capacitor, resulting in a plurality of intermediate voltages, having varying values between the supply voltage V_(DD) and the ground voltage V_(GND), at intermediate voltage nodes V_(int1)-V_(int2) located between the first MIM capacitor 404 a and the third MIM capacitor 404 c. For example, the first lower metal interconnect structure 402 a has a first intermediate voltage potential at a first intermediate voltage node V_(int1) (due to the voltage drop caused by the first MIM capacitor 404 a) and the second upper metal interconnect structure 412 b has a second intermediate voltage potential at a second intermediate voltage node V_(int2) (due to the voltage drop caused by the second MIM capacitor 404 b).

In some embodiments, the plurality of MIM capacitors 404 a-404 c may have a substantially same value. In such embodiments, the voltage dissipated by the plurality of MIM capacitors 404 a-404 c is equal. For example, for a first voltage potential with a value of V₁=1.2 V, a first voltage drop of the first MIM capacitor 404 a will be approximately 0.4 V, a second voltage drop of the second MIM capacitor 404 b will be approximately 0.4 V, and a third voltage drop of a third MIM capacitor 404 c will be approximately 0.4 V. The voltage drops result in a first intermediate voltage at V_(int1) of approximately 0.8 V and a second intermediate voltage at V_(int2) of approximately 0.4 V.

In some embodiments, the plurality of MIM capacitors 404 a-404 c may comprise bar shaped capacitors comprising a rectangular shaped lower electrode 406. A capacitor dielectric layer 408, having a plurality of lateral segments connected by vertical segments, contacts sidewalls of the lower electrode 406. An upper electrode 410 is arranged onto sidewalls and upper surfaces of the lateral segments of the capacitor dielectric layer 408. In alternative embodiments, the plurality of MIM capacitors 404 a-404 c may have alternate structures (e.g., a planar capacitor structure, a cup-shaped capacitor structure, etc.).

FIG. 5 illustrates some alternative embodiments of an integrated chip 500 comprising a voltage divider having a plurality of MIM capacitors.

Integrated chip 500 comprises a first MIM capacitor 504 a, a second MIM capacitor 504 b, and a third MIM capacitor 504 c arranged in series between a supply voltage V_(DD) and a ground voltage V_(GND). The first MIM capacitor 504 a has an upper electrode 510 connected to a first upper metal interconnect structure 512 a held at the supply voltage V_(DD) and a lower electrode 506 connected to a first lower metal interconnect structure 502 a. The first lower metal interconnect structure 502 a is connected to a second upper metal interconnect structure 512 b contacting an upper electrode 510 of the second MIM capacitor 504 b by way of a first via 514 a laterally separated from the first MIM capacitor 504 a. The second MIM capacitor 406 b has a lower electrode 506 connected to a second lower metal interconnect structure 502 b. The second lower metal interconnect structure 502 b is connected to a third upper metal interconnect structure 512 c contacting an upper electrode 510 of the third MIM capacitor 504 c by way of a second via 514 b laterally separated from the second MIM capacitor 504 b. The third MIM capacitor 504 c has a lower electrode 506 connected to a third lower metal interconnect structure 502 c held at the ground voltage V_(GND).

The first lower metal interconnect structure 502 a has a first intermediate voltage potential at a first intermediate voltage node V_(int1) (due to the voltage drop caused by the first MIM capacitor 504 a) and the second metal interconnect structure 502 b has a second intermediate voltage potential at a second intermediate voltage node V_(int2) (due to the voltage drop caused by the second MIM capacitor 504 b).

In some embodiments, MIM capacitors 504 a-504 c may comprise dual damascene capacitors comprising a ‘U’ shaped capacitor dielectric layer 508 nested within a ‘U’ shaped lower electrode 506, and a rectangular shaped upper electrode 510 nested within the ‘U’ shaped capacitor dielectric layer 508. In other embodiments, the MIM capacitors 504 a-504 c may have alternate structures (e.g., a planar capacitor structure, a bar-shaped capacitor structure, etc.)

FIG. 6 illustrates some alternative embodiments of an integrated chip 600 comprising a voltage divider having a plurality of MIM capacitors.

Integrated chip 600 comprises a first MIM capacitor 604 a, a second MIM capacitor 604 b, and a third MIM capacitor 604 c arranged in series between a supply voltage V_(DD) and a ground voltage V_(GND). The first MIM capacitor 604 a has an upper electrode 610 connected to a first upper metal interconnect structure 612 a held at the supply voltage V_(DD) and a lower electrode 606 connected to a first lower metal interconnect structure 602 a. The first lower metal interconnect structure 602 a continuously extends between the lower electrode 606 of the first MIM capacitor 604 a and a lower electrode 606 of the second MIM capacitor 604 b. The second MIM capacitor 604 b has an upper electrode 610 connected to a second upper metal interconnect structure 612 b. The second upper metal interconnect structure 612 b is connected to a second lower metal interconnect structure 602 b contacting a lower electrode 606 of the third MIM capacitor 604 c by way of a via 614 laterally separated from the second MIM capacitor 604 b. The third MIM capacitor 604 c has an upper electrode 610 connected to a third upper metal interconnect structure 612 c held at the ground voltage potential V_(GND).

The first lower metal interconnect structure 602 a has a first intermediate voltage potential at a first intermediate voltage node V_(int1) (due to the voltage drop caused by the first MIM capacitor 604 a) and the second upper metal interconnect structure 612 b has a second intermediate voltage potential at a second intermediate voltage node V_(int2) (due to the voltage drop caused by the second MIM capacitor 604 b).

In some embodiments, a metal connection layer 616 may be arranged between the upper electrode 610 and the first upper metal interconnect structure 612 a to account for differences in height between the first MIM capacitor 604 a and a laterally adjacent via layer (e.g., a via layer in an embedded memory region or a logic region located on another area of an integrated chip). The metal connection layer 616 may comprise a same material as the first upper metal interconnect structure 612 a (e.g., copper).

In some embodiments, the MIM capacitors 604 a-604 c may comprise planar capacitors comprising lower electrode 606 that is substantially planar (i.e., flat), a capacitor dielectric layer 608 that is substantially planar, and an upper electrode 610 that is substantially planar. In alternative embodiments, the MIM capacitors 604 a-604 c may have alternate structures (e.g., a dual damascene capacitor structure, a cup-shaped capacitor structure, etc.).

Although FIGS. 3-6 illustrate integrated circuits having two or three MIM capacitors connected in series, the present disclosure is not limited to such configurations. Rather, the disclosed voltage divider may comprise any number of MIM capacitors. For example, in some embodiments, the disclosed voltage divider may comprise n MIM capacitors connected in series. In some embodiments, wherein the n MIM capacitors have substantially equal capacitance values, the resulting voltage divider will divide an input signal V_(DD) into n−1 intermediate output voltages having voltage values equal to V_(DD)−m/n*V_(DD), wherein m is the number of decoupling capacitors between an intermediate output node and the input signal V_(DD).

FIG. 7 illustrates some embodiments of an integrated chip 700 comprising disclosed voltage divider comprising a plurality of MIM decoupling capacitors.

The integrated chip 700 comprises a decoupling region 701 a, an embedded memory region 701 b, and a logic region 701 c. A plurality of separate dielectric layers 702 a-702 e are stacked onto one another over a substrate 102. The plurality of separate dielectric layers 702 a-702 e may comprise one or more of a same dielectric material or one or more different dielectric materials.

The decoupling region 701 a comprises a voltage divider 703. The voltage divider 703 comprises a plurality of MIM capacitors 706 a-706 b having a lower electrode 708 separated from an upper electrode 712 by way of a capacitor dielectric layer 710. The plurality of MIM capacitors 706 a-706 c are connected in series between a supply voltage V_(DD) and a ground voltage V_(GND) by a conductive path comprising a lower metal wire layer 704 c and/or an upper metal wire layer 704 d and/or a via layer 714 c. In some embodiments, the supply voltage V_(DD) may be provided by a power rail configured to provide the supply voltage to other areas of the integrated chip (e.g., to the embedded memory region 701 b and the logic region 701 c).

The lower metal wire layer 704 c may be vertically separated from the underlying substrate 102 by way of one or more dielectric layers 702 a-702 d. In various embodiments, the one or more dielectric layers 702 a-702 d may comprise a low-k dielectric layer, an ultra low-k dielectric layer, an extreme low-k dielectric layer, and/or an oxide layer. In some embodiments, the lower metal wire layer 704 c may be vertically separated from one or more underlying transistor devices 705. In some embodiments, the lower metal wire layer 704 c and/or the upper metal wire layer 704 d may comprise copper metal wires.

An intermediate voltage node V_(int1) is located along the conductive path extending between the plurality of MIM capacitors 706 a-706 b. The intermediate voltage node V_(int1) has a voltage potential between the supply voltage V_(DD) and the ground voltage V_(GND). The intermediate voltage node V_(int1) provides for voltage drops over the plurality of MIM capacitors 706 a-706 b that are smaller than a reliability voltage limit (e.g., time dependent dielectric breakdown voltage, etc.) of the plurality of MIM capacitors 706 a-706 b. This allows the plurality of MIM capacitors 706 a-706 b to be used as decoupling capacitors configured to maintain a constant voltage between the supply voltage V_(DD) and the ground voltage V_(GND), so as to reduce switching noise on a power rail that supplies the supply voltage V_(DD) to the other areas of the integrated chip 700.

In various embodiments, the plurality of MIM capacitors 706 a-706 b can be located at any location within a BEOL metallization stack. For example, in various embodiments, the plurality of MIM capacitors 706 a-706 b can be located in dielectric layer 702 c between M1 (a first metal wire layer in a BEOL metallization stack) and M2 (a second metal wire layer in the BEOL metallization stack), in dielectric layer 702 d between M2 and M3, in dielectric layer 702 e between M3 and M4, etc.

The embedded memory region 701 b is laterally offset from the decoupling region 701 a and comprises a plurality of RRAM cells 706 c-706 d. The plurality of RRAM cells 706 c-706 d comprise a lower electrode 708 vertically separated from an upper electrode 712 by a capacitor dielectric layer 710. The upper electrode 712 is connected to a bit line BL (e.g., arranged within an overlying metal interconnect layer), which is coupled to control circuitry such as a row/column decoder or a sense amplifier. The lower electrode 708 is connected to the lower metal wire layer 704 c, which is further connected to a first source/drain region 717 a of an underlying transistor device 716 by way of one or more metal layers (e.g., a conductive contact 718, a first metal wire layer 704 a, a first metal via layer 714 a, a second metal wire layer 704 b, and a second metal via layer 714 b). A second source/drain region 717 b of the transistor device 716 is connected to a source line SL by way of one or more additional metal layers. A word line (WL) for addressing the plurality of RRAM cells 706 c-706 d is coupled to a gate electrode 716 g of the transistor device 716.

The lower electrode 708 and the upper electrode 712 of the plurality of RRAM cells 706 c-706 d and the lower electrode 708 and the upper electrode 712 of the plurality of MIM capacitors 706 a-706 b may be a same material. Similarly, the capacitor dielectric layer 710 of the plurality of RRAM cells 706 c-706 d and the capacitor dielectric layer 710 of the plurality of MIM capacitors 706 a-706 b may be a same material. In some embodiments, plurality of MIM capacitors 706 a-706 b and the plurality of RRAM cells 706 c-706 d may be located within a same dielectric layer (i.e., at a substantially same vertical location in a BEOL metallization stack). In other embodiments, the plurality of MIM capacitors 706 a-706 b and the plurality of RRAM cells 706 c-706 d may be located within a different dielectric layer (i.e., at a different vertical location in the BEOL metallization stack).

In some embodiments, the plurality of MIM capacitors 706 a-706 b and the plurality of RRAM cells 706 c-706 d have a same structure (i.e., a same size, a same shape, same layers). For example, in some embodiments, a capping layer (not shown) may be located between the capacitor dielectric layer 710 and the upper electrode 712 of the plurality of MIM capacitors 706 a-706 b and the plurality of RRAM cells 706 c-706 d. The capping layer is configured to store oxygen, which can facilitate resistance changes within the capacitor dielectric layer 710. In some embodiments, the capping layer may comprise a metal or a metal oxide that is relatively low in oxygen concentration (e.g., titanium (Ti), hafnium (Hf), platinum (Pt), and/or aluminum (Al), titanium oxide (TiO_(X)), hafnium oxide (HfO_(X)), zirconium oxide (ZrO_(X)), germanium oxide (GeO_(X)), or cesium oxide (CeO_(X))). In other embodiments, a hard mask layer may be arranged over the upper electrode 712 of the plurality of MIM capacitors 706 a-706 b and the plurality of RRAM cells 706 c-706 d.

The logic region 701 c comprises a plurality of metal layers laterally offset from the decoupling region 701 a and the embedded memory region 701 b. The plurality of metal layers comprise conductive contacts 718, metal wire layers 704, and metal via layers 714, vertically inter-leaved within the dielectric layers 702 a-702 e. For example, a first dielectric layer 702 a may comprise a conductive contact 718 of tungsten, a second dielectric layer 702 b may comprise a metal wire layer 704 a of copper, a third dielectric layer 702 c may comprise a metal via layer 714 a of copper, etc. In some embodiments, a metal via layer (e.g., 714 c) within the logic region 701 c may be at a same vertical position within the BEOL metallization stack (i.e., be vertically aligned with) as the plurality of RRAM cells 706 c-706 d within the embedded memory region 701 b and the plurality of MIM capacitors 706 a-706 b within the decoupling region 701 a. For example, metal via layer 714 c, the RRAM cells 706 c-706 d, and the MIM capacitors 706 a-706 b may have lower surfaces that are arranged along a horizontal plane.

FIGS. 8-13 illustrates cross-sectional views 800-1300 showing a method of forming an integrated chip comprising a voltage divider having a plurality of MIM structures.

As shown in cross-sectional view 800 of FIG. 8, a substrate 102 is provided. In various embodiments, the substrate 102 may comprise any type of semiconductor body (e.g., silicon/CMOS bulk, SiGe, SOI, etc.) such as a semiconductor wafer or one or more die on a wafer, as well as any other type of semiconductor and/or epitaxial layers formed thereon and/or otherwise associated therewith. The substrate 102 comprises a decoupling region 701 a and an embedded memory region 701 b. In some embodiments, the embedded memory region 701 b and/or the decoupling region 701 a may comprise a transistor device 716 located within the substrate 102.

A plurality of dielectric layers 702 a, 702 b, and 802 are formed within a BEOL metallization stack 801 over the substrate 102. The plurality of dielectric layers 702 a, 702 b, and 802 may comprise a low-k dielectric material, an ultra low-k dielectric material, an extreme low-k dielectric material, and/or an oxide. In some embodiments, the plurality of dielectric layers 702 a, 702 b, and 802 may be formed by way of a deposition process (e.g., chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), etc.). In some embodiments, one or more metal layers may be formed within the dielectric layers 702 a and 702 b within the embedded memory region 701 b, but not within the decoupling region 701 a.

As shown in cross-sectional view 900 of FIG. 9, dielectric layer 702 c is selectively exposed to an etchant 902 (e.g., CF₄, CHF₃, C₄F₈, HF, etc.) configured to selectively etch the dielectric layer 702 c to form a plurality of via holes 904 and a plurality of metal trenches 906.

As shown in cross-sectional view 1000 of FIG. 10, a via layer 714 a and a lower metal wire layer 704 b comprising one or more lower metal interconnect structures are formed by depositing a conductive material (e.g., copper and/or aluminum) within the plurality of via holes 904 and the plurality of metal trenches 906, respectively. In some embodiments, a deposition process may be used to form a seed layer within the plurality of via holes, followed by a subsequent plating process (e.g., an electroplating process, an electro-less plating process) that forms the metal material to a thickness that fills the plurality of via holes and metal trenches. In some embodiments, a chemical mechanical polishing (CMP) process may be used to remove excess of the metal material from a top surface of the dielectric layer 702 c. Although cross-sectional views 900-100 illustrate the lower metal wire layer 704 b and the via layer 714 a being formed by a dual damascene process, it will be appreciated that in alternative embodiments a single damascene process may be used to form the layers.

As shown in cross-sectional view 1100 of FIG. 11, a plurality of MIM capacitors 706 a-706 b and RRAM cells 706 c are formed over the lower metal wire layer 704 b. The plurality of MIM capacitors 706 a-706 b and RRAM cells 706 c respectively comprise a lower electrode 708 separated from an upper electrode 712 by a capacitor dielectric layer 710.

The plurality of MIM capacitors 706 a-706 b and RRAM cells 706 c may be formed using a same process. The same process uses a same mask set and same materials to form the lower electrode 708, the upper electrode 712, and the capacitor dielectric layer 710 for both the plurality of MIM capacitors 706 a-706 b and RRAM cells 706 c. For example, in some embodiments, the plurality of MIM capacitors 706 a-706 b and RRAM cells 706 c may be formed by depositing a bottom electrode layer over the lower metal wire layer 704 b, a capacitive dielectric layer over the bottom electrode layer, and an upper electrode layer over the capacitive dielectric layer. A masking layer is then selectively formed over the upper electrode layer, and the upper electrode layer and the capacitive dielectric layer are selectively etched according to the hard mask layer to form an upper electrode 712 by a capacitor dielectric layer 710 for the plurality of MIM capacitors 706 a-706 b and RRAM cells 706 c. The lower electrode layer may be subsequently etched according to the upper electrode 712 to form a lower electrode 708 for the plurality of MIM capacitors 706 a-706 b and RRAM cells 706 c.

In some embodiments, the lower electrode 708 and the upper electrode 712 may comprise a conductive material such as titanium nitride (TiN), tantalum nitride (TaN), tungsten (W) or copper (Cu). In some embodiments, the dielectric layer may comprise a high-k dielectric material, such as hafnium oxide (HfO_(X)), zirconium oxide (ZrO_(X)), aluminum oxide (AlO_(X)), nickel oxide (NiO_(X)), tantalum oxide (TaO_(X)), or titanium oxide (TiO_(X)).

As shown in cross-sectional view 1200 of FIG. 12, a dielectric layer 702 d is formed over the plurality of MIM capacitors 706 a-706 b and RRAM cells 706 c. The dielectric layer 702 d may be formed by way of a deposition process (e.g., CVD, PVD, ALD, etc.).

As shown in cross-sectional view 1300 of FIG. 13, a via layer 714 b and an upper metal wire layer 704 d comprising one or more upper metal interconnect structures are formed in the upper dielectric layer 702 d. The via layer 714 b vertically extends between metal wire layer 704 c and metal wire layer 704 d. One or more of the upper metal wire layer 704 d, the lower metal wire layer 704 b, and the via layer 714 b connect the plurality of MIM capacitors 706 a-706 b in a series connection without connecting the RRAM cells 706 c in a series connection.

In some embodiments, the via layer 714 b and the upper metal wire layer 704 d may be formed using a dual damascene process, which selectively exposes dielectric layer 702 d to an etchant (e.g., CF₄, CHF₃, C₄F₈, HF, etc.) configured to form a plurality of via holes and a plurality of metal trenches overlying the plurality of via holes. A metal material (e.g., copper, aluminum, etc.) is subsequently formed in the plurality of via holes and metal trenches.

FIG. 14 illustrates some additional embodiments of an integrated chip comprising disclosed voltage divider circuit comprising MIM capacitors.

While method 1400 is described herein as a series of acts or events, it will be appreciated that the illustrated ordering of such acts or events are not to be interpreted in a limiting sense. For example, some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein. In addition, not all illustrated acts may be required to implement one or more aspects or embodiments of the description herein. Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases. Although method 1400 is described in relation to FIGS. 8-13, it will be appreciated that the method 1400 is not limited to such structures, but instead may stand alone as a method independent of the structures.

At 1402, a lower inter-level dielectric (ILD) layer is formed over a substrate. FIG. 8 illustrates some embodiments of a cross-sectional view 800 corresponding to act 1402.

At 1404, one or more lower metal interconnect structures are formed within a lower metal layer disposed within the lower ILD layer. FIGS. 9-10 illustrates some embodiments of cross-sectional views 900-1000 corresponding to act 1404.

At 1406, a plurality of MIM (metal-insulator-metal) structures are formed over the one or more lower metal interconnect structures in a decoupling region. FIG. 11 illustrates some embodiments of a cross-sectional view 1100 corresponding to act 1406.

At 1408, in some embodiments, a plurality of RRAM cells may be concurrently formed in an embedded memory region laterally adjacent to the decoupling region. FIG. 11 also illustrates some embodiments of a cross-sectional view 1100 corresponding to act 1408.

At 1410, an upper ILD layer is formed over the plurality of MIM structures. FIG. 12 illustrates some embodiments of a cross-sectional view 1200 corresponding to act 1410.

At 1412, one or more upper metal interconnect structures are formed within the upper ILD layer overlying the plurality of MIM structures. The one or more upper metal interconnect structures and/or the one or more lower metal interconnect structures are arranged within a conductive path that electrically couples the plurality of plurality of RRAM cells in a series connection. In some embodiments, a via layer may also be formed within the upper ILD layer, at a location within the conductive path that is vertically between the one or more upper metal interconnect structures and the one or more lower metal interconnect structures. FIG. 13 illustrates some embodiments of a cross-sectional view 1300 corresponding to act 1412.

Therefore, the present disclosure relates to a method of forming an integrated circuit having a plurality of MIM decoupling capacitors connected in series between a first voltage potential and a second voltage potential to prevent damage to the MIM decoupling capacitors, and an associated structure

In some embodiments, the present disclosure relates to a method of forming an integrated chip. The method comprises forming one or more lower metal interconnect structures within a dielectric layer over a substrate. The method further comprises forming a plurality of MIM (metal-insulator-metal) structures over the one or more lower metal interconnect structures. The method further comprises forming one or more upper metal interconnect structures over the plurality of MIM structures, wherein the one or more lower metal interconnect structures or the one or more upper metal interconnect structures electrically couple the plurality of MIM structures in a series connection.

In other embodiments, the present disclosure relates to a method of forming an integrated chip. The method comprises forming one or more lower metal interconnect structures within a lower inter-level dielectric (ILD) layer over a semiconductor substrate. The method further comprises forming a plurality of MIM (metal-insulator-metal) capacitors over the one or more lower metal interconnect structures over a first region of the semiconductor substrate, and a plurality of RRAM cells over a second region of the semiconductor substrate. The method further comprises forming an upper ILD layer over the plurality of MIM capacitors and the plurality of RRAM cells. The method further comprises forming one or more upper metal interconnect structures within the upper ILD layer, wherein the one or more lower metal interconnect structures or the one or more upper metal interconnect structures are comprised within a conductive path that electrically couples the plurality of MIM capacitors in a series connection.

In yet other embodiments, the present disclosure relates to an integrated chip. The integrated chip comprises a substrate and a lower metal interconnect layer having one or more lower metal interconnect structures arranged within a lower ILD layer over the substrate. The integrated chip further comprises a plurality of MIM (metal-insulator-metal) structures arranged over the lower metal interconnect layer. The integrated chip further comprises an upper metal interconnect layer having one or more upper metal interconnect structures arranged within an upper ILD layer over the plurality of MIM structures, wherein the one or more lower metal interconnect structures or the one or more upper metal interconnect structures are comprised within a conductive path that electrically couples the plurality of MIM structures in a series connection.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. A method of forming an integrated chip, comprising: forming one or more lower metal interconnect structures within a dielectric layer over a substrate; forming a plurality of MIM (metal-insulator-metal) structures over the one or more lower metal interconnect structures, wherein the plurality of MIM structures respectively comprise a lower electrode separated from an upper electrode by a first dielectric layer; forming one or more upper metal interconnect structures over the plurality of MIM structures, wherein the one or more lower metal interconnect structures or the one or more upper metal interconnect structures electrically couple the plurality of MIM structures in a series connection; forming a plurality of RRAM cells concurrent with forming the plurality of MIM structures, wherein the plurality of RRAM cells are formed in an embedded memory region laterally separated from a decoupling region comprising the plurality of MIM structures, wherein the plurality of RRAM cells respectively comprise a second lower electrode separated from a second upper electrode by a second dielectric layer; and wherein the lower electrode is a same material as the second lower electrode, the upper electrode is a same material as the second upper electrode, and the first dielectric layer is a same material as the second dielectric layer.
 2. The method of claim 1, wherein the one or more lower metal interconnect structures comprise a metal wire layer extending in a lateral direction parallel to an upper surface of the substrate.
 3. The method of claim 2, wherein at least one of the plurality of MIM structures have an electrode in direct contact with the one or more lower metal interconnect structures.
 4. The method of claim 2, wherein the one or more lower metal interconnect structures comprise copper.
 5. The method of claim 1, wherein the lower electrode and the upper electrode comprise platinum (Pt), aluminum-copper (AlCu), titanium nitride (TiN), gold (Au), titanium (Ti), tantalum (Ta), tantalum nitride (TaN), tungsten (W), tungsten nitride (WN), or copper (Cu).
 6. The method of claim 1, wherein the first dielectric layer comprises nickel oxide (NiO), titanium oxide (TiO), hafnium oxide (HfO), zirconium oxide (ZrO), zinc oxide (ZnO), tungsten oxide (WO₃), aluminum oxide (Al₂O₃), tantalum oxide (TaO), molybdenum oxide (MoO), or copper oxide (CuO).
 7. The method of claim 1, wherein the one or more lower metal interconnect structures comprise a first lower metal interconnect structure that extends between a lower electrode of a first one of the plurality of MIM structures and a lower electrode of a second one of the plurality of MIM structures.
 8. The method of claim 1, wherein the plurality of MIM structures in a series connection between a first voltage potential and a second voltage potential, and wherein the first voltage potential has a value that is greater than a dielectric breakdown voltage of the plurality of MIM structures.
 9. A method of forming an integrated chip, comprising: forming one or more lower metal interconnect structures within a lower inter-level dielectric (ILD) layer over a semiconductor substrate; forming a plurality of MIM (metal-insulator-metal) capacitors over the one or more lower metal interconnect structures over a first region of the semiconductor substrate, wherein the plurality of MIM capacitors respectively comprise a lower electrode separated from an upper electrode by a first dielectric layer; forming a plurality of memory cells concurrent with forming the plurality of MIM capacitors, wherein the plurality of memory cells respectively comprise a second lower electrode separated from a second upper electrode by a second dielectric layer; forming an upper ILD layer over the plurality of MIM capacitors and the plurality of memory cells; forming one or more upper metal interconnect structures within the upper ILD layer, wherein the one or more lower metal interconnect structures or the one or more upper metal interconnect structures are comprised within a conductive path that electrically couples the plurality of MIM capacitors in a series connection; and wherein the lower electrode is a same material as the second lower electrode, the upper electrode is a same material as the second upper electrode, and the first dielectric layer is a same material as the second dielectric layer.
 10. The method of claim 9, wherein the plurality of MIM capacitors and the plurality of memory cells have lower surfaces that are arranged along a horizontal plane.
 11. An integrated chip, comprising: a substrate; a lower metal interconnect layer having one or more lower metal interconnect structures arranged within a lower ILD layer over the substrate; a plurality of MIM (metal-insulator-metal) structures arranged over the lower metal interconnect layer, and respectively comprising a first lower electrode separated from a first upper electrode by a first dielectric layer; a plurality of memory cells arranged over the lower metal interconnect layer, and respectively comprising a second lower electrode separated from a second upper electrode by a second dielectric layer; an upper metal interconnect layer having one or more upper metal interconnect structures arranged within an upper ILD layer over the plurality of MIM structures and the plurality of memory cells, wherein the one or more lower metal interconnect structures or the one or more upper metal interconnect structures are comprised within a conductive path that electrically couples the plurality of MIM structures in a series connection; and wherein the first lower electrode is a same material as the second lower electrode, the first upper electrode is a same material as the second upper electrode, and the first dielectric layer is a same material as the second dielectric layer.
 12. The integrated chip of claim 11, wherein the one or more lower metal interconnect structures comprise a metal wire layer extending in a lateral direction parallel to an upper surface of the substrate.
 13. The integrated chip of claim 11, wherein at least one of the plurality of MIM structures comprises a lower electrode in direct contact with the one or more lower metal interconnect structures.
 14. The integrated chip of claim 11, wherein at least one of the plurality of MIM structures comprises: an upper electrode; and a metal connection layer arranged between the upper electrode and the one or more upper metal interconnect structures, wherein the metal connection layer comprises a same material as the one or more upper metal interconnect structures.
 15. The integrated chip of claim 12, further comprising: one or more dielectric layers vertically arranged between the metal wire layer and the substrate, wherein the one or more dielectric layers comprise additional metal wire layers.
 16. The integrated chip of claim 11, wherein the plurality of memory cells are aligned with the plurality of MIM structures and arranged in an embedded memory region laterally separated from a decoupling region comprising the plurality of MIM structures.
 17. The integrated chip of claim 11, wherein the lower ILD layer is vertically separated from the substrate by one or more additional inter-level dielectric layers.
 18. The integrated chip of claim 11, wherein the lower metal interconnect layer comprises copper.
 19. The integrated chip of claim 11, wherein the lower metal interconnect layer is vertically separated from the substrate by one or more additional inter-level dielectric layers.
 20. The integrated chip of claim 11, wherein the plurality of MIM structures comprise a first MIM capacitor and second MIM capacitor that are connected in series between by way of a single metal layer continuously extending between the first MIM capacitor and the second MIM capacitor. 